Rare virus kills thousands of farmed trout

Thousands of rainbow trout have been killed by a rare virus that is posing "a very serious threat" to stocks, the government said yesterday. Fish have died or been destroyed in an outbreak on a farm in Yorkshire and movement restrictions have been placed on more than 30 other premises in an area from the Pennines to the coast near Scarborough and Bridlington. Fisheries officials are also checking on the health of wild fish across the catchment area of the river Ouse after the first case of viral haemorrhagic septicaemia (VHS) in mainland Britain.

The only other known instance was on the Scottish island of Gigha in farmed turbot in 1994, but the disease has caused significant losses at trout farms elsewhere in Europe. The government and industry officials said there were no risks to human health.

"It is exceedingly bad news," said Nick Read, the chairman of the British Trout Association. "Yorkshire is one of the important trout growing areas for the country. Some [of the farms] are key to other areas of the country. They run hatcheries or produce fingerlings [young trout] that are grown on in other areas."

The outbreak was confirmed last Friday at an unidentified farm which raises fish for food. Nineteen tonnes of fish either died from the disease or were slaughtered through electronic stunning in the water. It is not known exactly how much stock that represents, but there can be as many as 3,000 fully grown fish to the tonne. The farm site is to be drained and disinfected.

Experts are trying to identify whether the virus came from other fish farms in the area, another part of the country or wild fish.